Hydraulically actuated clutch and brake mechanism



Oct. 24, 1950 M. M. COKER 2,526,935

HYDRAULICALLY ACTUA'I'ED CLUTCH AND BRAKE MECHANISM Filed Dec. 22, 1947 3 Sheets-Sheet 1 INVENTOR.

W r/M i! 6016 4/. 4 1 2 A T T ORNE Y Oct. 24, 1950 M. M. COKER 2,526,935

HYDRAULICALLY ACTUATED CLUTCH AND BRAKE MECHANISM Filed Dec. 22, 1947 3 Sheets-Sheet 2 A TTORNEY Patented Oct. 24, 1950 2,526,935

UNITED STATES PATENT OFFICE HYDRAULICALLY ACTUATED CLUTCH AND BRAKE MECHANISM Morton M. Colrer, Peoria, 111., assignor to Caterpillar Tractor 00., Peoria, 111., a corporation of California Application December 222, i947, Serial No. 793,258

2 Claims.

This invention relates to a hydraulic control means for a cable winding drum or winch and more particularly to means for hydraulically actuating the control levers of such a mechanism.

The invention is particularly adapted for use on a cable winding drum or winch associated with a tractor or like vehicle and powered by a suitable power take-of! therefrom. It is conventional practice to provide such mechanisms with a clutch for transmitting power to the cable winding drum and a brake for preventing rotation of the drum when the clutch is disengaged.

Usually such devices are provided with manually actuated levers for efiecting engagement and disengagement of the clutch and brake. However, in many installations where it is desirable to have the operator stationed some distance away, the controls become quite complicated and require considerable eflort on the part of the operator to actuate them.

In order to overcome the above mentioned and other diillculties it is an object or! this invention to associate a hydraulically actuated piston with each of the control levers, such pistons being actuated by hydraulic pressure, and controlled by a single control valve. It is a further object of this invention to provide a control valve having a spring loaded relief, the spring load of which can be varied permitting an increase in the force acting on the hydraulic pistons. Further and more specific objects and advantages of this invention are made apparent in the following specification wherein a preferred form of the invention is described in detail by reference to the accompanying drawings.

For purposes of illustration, the invention is disclosed herein as associated with a cable control mechanism of the kind employed on a tractor wherein a power take-ofi shaft. of the tractor is connected with a cable spooling mechanism, such as is disclosed in assignees co-pending application of John W. Bridwell Serial No. W132i, filed October '7, 1946, entitled Mechanical Brake and Clutch Control. Its adaptability to other uses will however be readily apparent as the description proceeds.

In the drawings:

Fi 1 is a side elevation of a cable winding drum embodying the present invention with poro tions broken away to illustrate more clearly the control linkage thereof;

Fig. 2 is a longitudinal, sectional view of the control valve and fluid pump illustrating the control valve in a neutral position; and

Fig. 3 is a longitudinal, sectional view of the control valve illustrating a position to effect, disengagement of the brake and engagement of the clutch.

In Fig. l of the drawings, a control valve i8 is shown as being rigidly secured by means of cap screws H to a housing 12 of a cable control unit such as is normally associated with a tractor or like vehicle and which serves to control a bulldozer or similar mechanism associated with the tractor. The cable control unit does not form a part of the present invention but the principal portions will be generally described in order to facilitate an understanding of the manner in which the invention functions.

The cable control unit comprises a cable winding drum (not shown) which is powered for retation by a suitable power take-ofi from the tractor and which is provided with a clutch for transmitting such power. Engagement and disengagement of the clutch is effected by a control lever l3. A brake drum i4 is formed integrally with the cable winding drum and is encircled by a brake band l5, one end of which is anchored to a bracket l6, rigidly secured to the housing I2 by means of capscrews H. The opposite end of the brake band is connected by means of an adjustable link l8 to an arm I9, formed integrally with a brake control lever 20. The control lever 20 is pivotally mounted about a pin 2| which is supported within a bracket 22 rigidly secured to the housing i2 by means of capscrews 23. The extending end of the brake lever 20 is connected to a spring 24, the opposite end of which is anchored to the housing I2.

The action of the spring 24 causes the lever 20 to pivot about the pin 2! which in turn urges the brake band into frictional engagement with the brake drum I4. The arrangement is such that when it is desired to take in on the cable associated with the cable winding drum the clutch must be engaged and the brake must be disengaged by overcoming the force of the spring 24 which normally urges the brake into engagement.

The control valve is provided with manual control linkage comprising a link 25, a bellcrank lever 20, and a control rod, a portion of which is indicated at 21, and which may extend to the tractor operators' station (not shown). The control valve serves to direct fluid through a pair of hydraulic lines 28 and 29 to a pair of hydraulic jacks 30 and 3|, such jacks being rigidly secured to the bracket 22. Slidably disposed within each of the jacks l0 and 3| is a asaacss piston (not shown), such pistons being provided with piston rods 32 and 53. The piston rod 82 is pivotally connected to the clutch control lever is so that when fluid is directed to the Jack 35 the rod 32 is extended eflecting engagement of the clutch. A spring 34 is connected to the extending end of the clutch control lever I3 and the opposite end of the spring is anchored to a lug 35 formed integrally with the Jack 55. The spring 34 opposes the action of the Jack and serves to return the clutch control lever I3 to a disengaged position when hydraulic pressure is not applied to the jack.

The piston rod 33 associated with the jack 3| is pivotally connected to an arm 35 formed integrally with the brake lever 25. When fluid is supplied to the jack 3| the rod 33 is extended causing the lever 25 to pivot about the pin 2| overcoming the force of the spring 24 and thus effecting disengagement of the brake. Rotation of the lever 25 is liinited by engagement of an adjustable stop screw 31 which is disposed within an arm 38 formed integrally with the brake lever 25 and which engages a lug 39 formed integrally with the bracket 22.

As is illustrated in Fig. 2, the control valve i is provided with an elongated bore 45 for the sliding reception of a valve spool 4|. The valve spool is provided with raised lands 42 and 43 which when the valve spool is manipulated serve selectively to direct fluid from the axial bore 45 through a drilled passage 44 to the hydraulic line 28 or through a second drilled passage 45 to the hydraulic line 29. The extending end of the valve spool 4| is received in a recess 45 provided in a sleeve 41 and rigidly connected thereto by means of a pin 48. The sleeve 41 extends from the control valve and is connected to the manual control link 25 illustrated in Fig. l. A pair of oil seals 49 are disposed within a counterbore 55 provided in the body of the control valve, such seals serving to effect an oil and dirt tight seal between the control valve body and the sleeve 41.

The valve spool 4| is normally held in a central or neutral position such as is illustrated in Fig, 2 by means oi. a spring 52 which is received in the counterbore 55 and which is interposed between a pair of washers 53 and 54. The washer 53 normally bears against the end of the land 42 on the spool valve and against a shoulder formed by the end of the counterbore 55. The washer 54 normally bears against the sleeve 41 and against a spring retainer 55 which is held in place by a snap ring 58 disposed within a suitable recess in the counterbore 55. Disposed about the valve spool and encircled by the spring 52 is a spacing sleeve 51 which serves to limit the movement of the valve spool in a downward direction. A second spacing sleeve 58 is disposed about the spring 52 and serves to limit the movement of the valve spool in an upward direction.

A constant delivery oil pump 55 which is driven by a suitable power take-oil from the tractor (not shown) is rigidly secured to the body of the control valve l5 by means of cap screws 5|. The pump is enclosed within a housing 52 secured to the control valve by means of cap screws 53 to form a chamber 64 which serves as a fluid reservoir for the hydraulic system. The pump 85 is provided with inlet and outlet passages 55 and 58, the outlet passage 58 communicating with a passage 51 in the body of the control valve I5. Passage 5'! extends transversely through a sleeve member 58 and communicates with a passage H The sleeve is disposed within a counterbore 55 provided in the body 01 the control valve and is rigidly connected thereto by means of capscrews 15. The function of the sleeve 88 will be made apparent as the description proceeds. Thus fluid under pressure from the pump is admitted to the axial bore 45 by way of passages 51, II, and 45. Such fluid is returned from the bore 45 to the chamber 54 by way of passages l2, l3, and 14, the passage 14 being in communication with the counterbore 59 as well as with the passage 13 and chamber 54.

When the valve spool is in the position illustrated in Fig. 2, fluid from the pump is admitted to the axial bore 45 by way of drilled passages 51, H, and 45. However, as the passage 12 is open to the axial bore 45, such fluid is returned to the chamber 54 by way of drilled passages l2, l3, and 14. Under this free circulating condition the pressure within the system will not be sufficient to actuate the hydraulic jacks 35 and 8| illustrated in Fig. 1.

When it is desired to release the brake associated with the cable winding drum so that the cable is permitted to spool out in response to cable tension the spool valve is moved upwardly as viewed in Fig. 2 until the land 43 closes oi! the passage 45 preventing communication between the passage 45 and the axial bore 45. Under this condition all of the pressure from the pump will be directed through the hydraulic line 29 actuating the jack 3|. The land 43 is provided with an annular relief 15 which distributes this pressure equally around the periphery of the land thus preventing binding of the valve spool in the axial bore 45. When the pressure is directed through the conduit 29 the jack 3| is actuated causing the brake lever 25, illustrated in Fig. 1, to be rotated until the stop screw 31 contacts the lug 39 preventing further movement of lever 25. At this time the brake will be fully disengaged and at the same time the pressure within the hydraulic line 29 will rise. In order to prevent excessive pressure in the line 25 a spring loaded relief valve 15 is provided in the counterbore 59.

The relief valve is provided with an extending tubular stem-like portion which is disposed within and normally closes a passage ll provided in the sleeve 55. Valve 16 is urged toward its closed position by a spring 18 interposed between the relief valve and a spring retainer 19 seated against a shoulder formed by the end of the counterbore 59. When the pressure within the passage exceeds a predetermined value the spring I8 will be compressed permitting fluid from the passage 11 to flow through a plurality of apertures 19 provided in the hollow stem of the relief valve thu establishing communication between the passage 61 and the counterbore 69. Such fluid is returned from the counterbore 59 to the chamber 54 by way of the passage 14.

When it is desired to take in on the cable associated with the cable winding drum the valve spool is moved to the position illustrated in Fig. 3 in which position the land 42 closes on the passage l2 thus preventing fluid from being returned to the chamber 54 from the axial bore 45. Under this condition fluid under pressure will be directed through both conduit lines 28 and 29 actuating the jacks 35 and 3| shown in Fig. 1. Due to a diiIerential in the force exerted by the spring 34 associated with the clutch lever i3 and the spring 24 associated with the brake lever 25 the clutch which in turn communicates with the passage 45. 7 will be engaged first picking up the load and then the brake 24 will be released permitting the cable winding drum to be rotated takin in the cable.

Under some conditions it is desirable that an increased force be exerted on the clutch lever l3 to prevent slipping of the clutch due to high torque conditions during periods of overload. One of the advantages of this control is that by further movement of the valve spool 4| down- 7 wardly as viewed in Fig. 3, the end of the valve spool adjacent to the land 43 will contact the spring retainer I9 displacing it downwardly thus increasing the spring load acting on the pressure relief valve 16. By increasing the spring load acting on the pressure relief valve the pressure exerted on the jacks is proportionately increased resulting in the application of an increased force on the clutch urging it into tighter engagement.

A pair of passages 8| and 82 are provided in the control valve housing and serve to establish communication between the counterbore 50 and the drilled passage 13 thus equalizin the pressure in the counterbore 50 during movement of the valve spool 4| and preventing the formation of any hydraulic look.

I claim:

1. In a hydraulic control for a cable winding drum having a brake and a clutch, a hydraulic cylinder for engaging the clutch, a hydraulic cylinder for releasing the brake, a single control valve for directing fluid under pressure to both said cylinders, a spring loaded bypass valve to prevent excessive pressure in the cylinders, and means controlled by operation of the control valve to increase the load of the valve spring when greater pressure is required in the cylinders.

2. In a hydraulic control for a cable winding drum having a brake and a clutch, a hydraulic cylinder for engaging the clutch, a hydraulic cylinder for releasing the brake, a sliding spool type control valve for directing fluid under pressure to said cylinders, and a bypass for excessive pressure including a spring loaded valve with its spring disposed for engagement by the spool of the control valve to increase its load when greater pressure is required in the cylinders.

MORTON M. COKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,864,126 Ferris June 21, 1932 2,220,517 Friedman Nov. 5, 1940 2,270,431 Freeman Jan. 20, 1942 2,279,597 Selmer Apr. 14, 1942 2,308,299 Page 1 Jan. 12, 1943 2,366,433 Bridwell et al Jan. 2, 1945 2,392,421 Stephens Jan. 8, 1946 2,442,510 Peterson et al. June 1, 1948 

